Vapor intrusion resources for environmental professionals

Screening for the vapor intrusion pathway must be conducted at every contaminated site in Wisconsin. This page provides resources to help environmental consultants screen the vapor pathway, assess vapor risk and, where necessary, investigate and mitigate vapor intrusion at specific buildings. General information about vapor intrusion for property owners, tenants and the general public is available on the vapor intrusion page.

Community outreach

Community outreach

An effective outreach strategy that anticipates the needs and concerns of affected property owners and the community at large is important when vapor intrusion is involved. When citizens are well-informed about the issues surrounding a site, their questions and concerns can be more effectively addressed. Early two-way communication is essential for a successful investigation and mitigation effort. The following model letters and fact sheets are available for use with your outreach communications.

Template/model letters

The DNR created template letters to help environmental professionals communicate vapor intrusion investigations with affected property owners in plain, easily understood languauge. Because of the complex nature of vapor intrusion investigations, it is not possible to create a template letter for every situation. These template letters are yours to use as you see fit, in whole or in part.

DNR fact sheets

These fact sheets are intended to help environmental consultants and responsible parties communicate critical information about the vapor intrusion pathway to affected property owners. The fact sheets can be used in conjunction with template letters or as stand-alone documents. When planning an outreach strategy, decide which fact sheets and other tools best support the information you want to communicate to neighbors and other interested parties.

Environmental Contamination & Your Real Estate (RR-973) [PDF] - When soil or groundwater contamination is discovered in a rural or urban area, one of the questions that homeowners may raise is whether such information will impact the market value of their property and if so, to what extent. This publication discusses the issue.

Guidance

Guidance on addressing vapor intrusion

Vapor migration is a contaminant pathway that needs to be evaluated like other pathways. Its evaluation is required by NR 716.11(5)(a), (b), (g) and (h), Wis. Adm. Code.

Please note that the vapor screening levels found in the “Tables” section of EPA's 2002 guidance are out of date. To determine Wisconsin's vapor action levels for indoor air and vapor risk screening levels for sub-slab, soil gases and groundwater, please see the “screening levels” tab on this page.

Screening levels

Indoor air vapor action levels (VALs) are based on U.S. EPA's Regional Screening Level Tables [exit DNR], applying a 1 x 10-5 excess lifetime cancer risk. The "Quick Look-Up Table" provides VALs for select VOCs. It also provides information on how to convert indoor air concentration units and how to calculate groundwater to indoor air screening values. This table is updated semi-annually.

Please note: U.S. EPA changed the default risk exposure parameters in the May 2014 update to the Risk Screening Tables. This has resulted in a small increase to residential indoor air screening levels for compounds with a carcinogenic endpoint. The bold numbers in the Quick Look-up Table indicate which screening levels have changed since November 2013.

The U.S. EPA Vapor Intrusion Screening Level Calculator (VISL) and VISL User Guide [exit DNR] can be used to calculate DNR VALs for compounds not listed in the Quick Look-up Table. The user can use the drop-down check box beside the chemical name (listed alphabetically) to adjust the compounds viewed on the worksheet. The user should adjust the default target risk to 1x10-5 and choose the risk scenario (residential or commercial). The calculator will then provide the target indoor concentrations for the carcinogenic and non-carcinogenic endpoints. The DNR VAL is equal to the lesser of the two values.

Training

Issues and Trends Webinar - Vapor Intrusion Outreach "Toolkit"

Anticipating the needs and concerns of affected property owners and the community at large is critically important whenever vapor intrusion is involved. Clear and effective communication with them should be one of the goals of any outreach plan. To help with those efforts, DNR created a comprehensive toolkit of vapor intrusion communication materials to increase the consistency and effectiveness of communications between responsible parties and the public.

2011 Vapor Intrusion Issues in Wisconsin - FET Webinars

In March 2011, staff from the RR Program participated in two Federation of Environmental Technologists (FET) webinars about vapor intrusion issues in Wisconsin. The agenda, PowerPoint presentation slides and videos of the presentations are available below.